A stopcock is a cock or valve for stopping or regulating the flow of a fluid (wherein the term "fluid" as used herein may include liquids and/or gasses). In medicine, a stopcock is most typically used for regulating the flow of intravenous ("IV") fluids or medications into, or out of, a patient as part of an intravenous system. A stopcock can also be used to divert fluids or air into devices, such as for filling skin expanders with fluid or air during skin grafting, for filling breast implants with saline during breast augmentation procedures, for diverting spinal fluid into a manometer to measure spinal fluid pressure during a spinal tap, and for diluting viscous packed red blood cells with saline to make them less viscous for subsequent rapid infusion into the patient during transfusions.
Stopcocks have been in use in the practice of medicine for intravenous injection and infusions for more than 30 years. They provide a quick and sterile way for diverting intravenous fluid flow or medication into a patient by changing the flow path in the IV line system.
In the past six years, stopcocks have been used with increasing frequency as a needle-less intravenous injection port. That is, once the initial IV injection port has been opened using a first needle, subsequent injections and infusions are possible through the same injection port via a stopcock having three ports separated by a shut off valve. Stopcocks provide an inexpensive method of avoiding needle-stick injuries and for a clinician to comply with the FDA mandate "to use needle-less injection techniques whenever possible".
The first stopcocks used in medicine were made out of metal. They were re-sterilized and used on other patients. With the refining of plastic injection molding techniques, inexpensive, disposable plastic stopcocks have become the state of the art. They are disposed of after use on a single patient. The disposable plastic stopcock is cost effective and helps prevent spread of diseases between patients.
Early stopcocks were simply used as "on and off" valves to start or stop intravenous infusions. They contained two ports, an inlet port and an outlet port, which were placed in a straight line. There was a shut off lever in the middle of the two ports, and fluid flowed one way. These first stopcocks were designated as two-port, one-way stopcocks.
Another prior art stopcock has a body with three ports which are arranged in a T-shaped configuration, and a core having a lever and an axial portion. The channels and ports can be selected at the option of the user by rotating the lever to a position determined by the direction of flow desired. There is a "stop" tab on the body part of these stopcocks which prevents the lever of the stopcock from being turned to a position where all three ports are open and flow into one another at one time, i.e., such that the T-shaped path of the body and the T-shaped path of the core are fully aligned. Because fluid can flow three different ways, these stopcocks are designated as three-port, three-way stopcocks.
Referring to FIG. 1A, the prior art stopcock 2 is a three-port, four-way stopcock. It does not have a stop tab as in the three-port, three-way stopcock to prevent the lever from being turned to a position opposite the right angled port. The stopcock 2 includes a body 4 having an entry port 6, an exit port 8 and an injection port 10, and a core 12. The body 4 and the core 12 are molded as two separate parts and press-fit together to make a completed three-port, four-way stopcock 2. The core 12 includes a rotating axial portion 14 connected to a lever 16.
Referring to FIG. 1B and FIG. 1C, the axial portion 14 of the core 12 has a first flow channel 18, a second flow channel 20 and a third flow channel 22 which form a confluent "T" configuration. The lever 16 generally includes the word "off" 24 and an arrow 26 molded on its upper surface to show which direction fluid will not flow. The arrow 26 and the word "off" 24 do not directly indicate to the user which way the medication or fluid will flow.
The three-port, four-way stopcock 2 is a four-way stopcock because fluid can flow in four different ways. First, when the lever 16 points toward the entry port 6, fluid can flow between the injection port 10 and exit port 8. Second, when the lever 16 points toward the injection port 10, fluid can flow between the entry port 6 and exit port 8. Third, when the lever 16 points toward the exit port 8, fluid can flow between the entry port 6 and injection port 10. Finally, when the lever 16 points opposite the injection port 10, i.e., toward no port, fluid can flow between all three ports 6, 8, 10 at one time.
Referring to FIG. 2, the body 4 of the three-port, four-way stopcock 2 is molded as one piece. The entry port 6, exit port 8 and injection port 10 are located in a single horizontal plane and are confluent at a central chamber 28, which is filled with the axial portion 14 of the core 12 when the stopcock 2 is assembled. The entry port 6 has a female luer lock connector 30 and is the main fluid entry end of the stopcock 2. It usually is connected to a male luer-lock connector 32 from an IV set connected to a bag of IV fluid. The exit port 8 has a male luer lock or luer slip connector 32 and is the fluid exit end of the stopcock 2 and is usually connected to a female luer lock connector 30 of an IV extension set which ultimately connects to the IV catheter in the patient. The injection port 10 protruding perpendicularly from the middle of the straight line flow path formed by the entry port 6 and exit port 8 has a female luer lock connector 30 and is used for adding medication or fluids to the IV system.
Referring to FIG. 3, the axial portion 14 and the lever 16 are molded as one piece in a right angle configuration to form a completed core 12. The lever 16 rotates in a horizontal plane which is parallel to the horizontal plane formed by the three fluid flow ports 6, 8 and 10.
The procedure a clinician must follow to perform a typical IV injection or infusion using a conventional three-port, four-way stopcock 2 is fraught with difficulty and risk. An examination of this procedure makes clear the need for an improvement, such as that of the present invention described further below.
A typical intravenous setup using a three-port, four-way stopcock 2 has the exit port 8 typically connected to an IV extension tubing which is subsequently connected to an IV catheter in the patients vein. The entry port 6 is connected to a main IV administration set which is in turn connected to a bag of IV fluid, and the injection port 10 normally has a syringe or a secondary IV fluid line connected to it. When a syringe is attached to the injection port 10, the bulk and length of the syringe requires that the syringe-stopcock assembly sit on a surface wherein a single plane is formed by the flow ports 6,8,10 of the stopcock 2 and the attached syringe. The axial portion 14 then extends vertically upward from, and the lever 16 rotates in a plane parallel to, that surface. To turn the lever 16 in a desired direction, a first hand of a clinician is held palm up in a horizontal plane, with the fingers pointing upward in a vertical direction, to stabilize the syringe-stopcock assembly, and a second hand of the clinician is held above the lever 16, with fingers pointing in a downward, vertical direction, for grasping and rotating the lever 16.
This arrangement is awkward for the clinician. With the first hand below and the second hand above the stopcock 2, the clinician must first determine which way to turn the lever 16 to obtain the desired fluid flow, and then he or she must turn it in the correct direction, either clockwise or counter-clockwise, with fingers of the second hand. When the clinician is assured that the stopcock is secure in the grasp of the first hand only, the second hand releases the lever 16 and grasps the barrel of the syringe attached to the injection port 10. The second hand then pushes or pulls the plunger of the syringe to give an injection of medication or to aspirate fluid. The second hand must next move from the syringe barrel back to its previous position grasping the lever 16 of the stopcock 2 and rotating it back to its original position. This procedure is cumbersome and time consuming, and involves twice moving one hand between two perpendicular planes.
Referring to FIG. 4, there is shown another prior art stopcock. This stopcock is designated a four-port, three-way stopcock 34. Fluid can flow in three different ways. First, the fluid may flow between an entry port 36, an exit port 38, and a first lateral port 40, simultaneously. Second, fluid may flow between the entry port 36, exit port 38 and second lateral port 42 simultaneously. Third, fluid may flow between the entry port 36 and exit port 38 only. The stopcock 34 comprises a body 44 assembled with core 46. The core 46 has an axial portion 48 and a lever 50. The axial portion 48 sits partially inside a central chamber 52 of the body 44 and includes the entry port 36. The body includes the exit port 38, first lateral port 40 and second lateral port 42 which, together with the entry port 36, are confluent to the central chamber 52 such that the body 44 and the core 46 form an air-tight and a fluid-tight connection. The central chamber 52 is only partially filled with the axial portion 48 of the core 46 when the stopcock 34 is fully assembled. The axial portion 48 enters the body 44 through an opening opposite the exit port 38.
Referring to FIGS. 5A & 5B, the core 46 of the four-port, three-way stopcock is smaller in diameter, and shorter, than the body 44 of the stopcock 34. The lever 50 is built around the axial portion 48 about a third of the way down from its top end 54. The axial portion 48 is vertical and has a hollow cavity 55 at its center extending down its entire length. The axial portion 48 has a female luer connector 30 connected to its top end 54. A groove 56 is carved into the outer surface of the axial portion 48, beginning at its bottom end 58 and going about one third of the way up its length. An arrowshaped end 60 of the lever 50 points in the direction that the groove 56 faces. The groove 56 is separated from the hollow cavity 55 by a remaining thickness of material comprising the axial portion 48.
Referring back to FIG. 4, the axial portion 48 does not extend to the bottom of the central chamber 52. Thus, there is a small spacing 62 between the bottom of the central chamber 52 and the bottom end 58 of the axial portion, where the groove 56 begins. This spacing and the groove allow fluid to flow between the entry 36, exit 38 and either the first 40 or second 42 lateral ports, simultaneously, if the lever is pointed toward one of the two lateral ports 40, 42. If not, fluid merely flows between the entry 36 and exit 38 ports.
The four-port, three-way stopcock 34 has many drawbacks. First, it lacks the ability to selectively direct IV medications and IV fluids to specific ports and subsequently, to specific parts of the IV system. When the lever 50 is turned toward either of the lateral ports 40, 42, fluid flows between the entry 36, exit 38 and either one of the lateral ports 40, 42, simultaneously, instead of selectively between any two ports. Second, because of the design of the stopcock 34, fluid cannot be directed to flow between the lateral ports 40 and 42. Third, only one continuous flow path can run through the stopcock 34 at one time. Finally, fluid cannot be selectively, and specifically, diverted from either the entry 36 or exit 38 ports to either lateral port 40, 42 because the fluid flow path between the entry 36 and exit 38 ports cannot be shut off, i.e., some fluid will always flow between the entry 36 and exit 38 ports.